In BA on the QOTS (747) we have to load everything manually (SID/route/Star and winds) whereas on the light twin (777)
they just press a button and it magically appears frmo the ether.
It's no big deal and gives you something to before flight and at the start of the cruise before going to sleep
In reality all you have to do is string the airways together - the box works out the intersections for you. In practise it can be quicker manually loading a flight from LHR to USA than one from LHR to FCO!